Box Fill 314.16 B 4

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smbray

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This article states "For each yoke or strap containing one or more devices or equipment, a double volume allowance in accordance with Table 314.16B shall be made for each yoke or strap.........

The question is, what is meant by yoke or strap? I'm having a hard time interpreting this one as I thought of a yoke being the part of a device that screw mounts to the box which wouldn't make sense in this case, would it?
 
smbray said:
This article states "For each yoke or strap containing one or more devices or equipment, a double volume allowance in accordance with Table 314.16B shall be made for each yoke or strap.........

The question is, what is meant by yoke or strap? I'm having a hard time interpreting this one as I thought of a yoke being the part of a device that screw mounts to the box which wouldn't make sense in this case, would it?
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You are correct. The yoke, or strap, is the part that the 6-32 screws go through to mount the device to a box.
 
Yes, that would be the yoke of the device. So a single receptacle on one yoke would give equal 2 conductors. A duplex receptacle on one yoke would give you the same 2 conductor reduction. Three SP switches on one yoke would also give you a 2 conductor deduction. See where this is going? :wink:
 
smbray said:
So that means that 4 conductors need to be added to the fill calculation for each standard receptacle?
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No. You add two conductor size volumes to your fill calculation.

If your box has 14s, then add 2x2, or 4.00 in? to the equation. If is has 12s, you add 2x2.25, or 5.00in?. If you have more than one size, you add two of the largest.

If you have a two-gang box with two devices, you double that number. 3-gang box, triple it.

Keep in mind that the box fill calcs were developed before GFCI receps and high-power dimmers, so even though you may be 'legal' in your box fill figuring, it still may not all fit.
 
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Ok. Makes sense now. I was thinking that each receptacle or switch would have two yokes. One on top and one on bottom.
 
smbray said:
Ok. Makes sense now. I was thinking that each receptacle or switch would have two yokes. One on top and one on bottom.
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No, because you may run into something funky like this:

DSC05920a.jpg


And if you think all the funky stuff is old:

4swcombo.jpg




celtic said:
What happens in the case of a range or dryer recept.?

;)
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How many 10s, 8s and 6s do you splice in your dryer and range receps?
 
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I think a range or dryer is now a double "double" volume allowance per 2" wide nominal strap.(acutually 4 per device/strap) ie for #10 @ 2.5 X 4 = 10 cu in. I don't have the code book here. I think the end result is a range or dryer will now be in a 2 gang box.
 
jimman said:
I think a range or dryer is now a double "double" volume allowance per 2" wide nominal strap.(acutually 4 per device/strap) ie for #10 @ 2.5 X 4 = 10 cu in. I don't have the code book here. I think the end result is a range or dryer will now be in a 2 gang box.
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Per the 2008:


(4) Device or Equipment Fill.
For each yoke or strap containing
one or more devices or equipment, a double volume
allowance in accordance with Table 314.16(B) shall be
made for each yoke or strap based on the largest conductor
connected to a device(s) or equipment supported by that
yoke or strap. A device or utilization equipment wider than
a single 50 mm (2 in.) device box as described in Table
314.16(A) shall have double volume allowances provided​
for each gang required for mounting.

​
 
480sparky said:
If your box has 14s, then add 2x2, or 4.00 in? to the equation. If is has 12s, you add 2x2.25, or 5.00in?. If you have more than one size, you add two of the largest.
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Actually the way I read it, Each yoke or strap based on the largest conductor connected to a device or equipment supported by that yoke or strap.

so if I had a 2 gang box with 14awg going to a switch and a 12awg going to a gfci, then my device fill would be 8.50 not 9.00
 
isn't it easier to just use the deepest box you can, or does the extra cost add up too much? how much time does it take to figure box fill vs just using a deeper (more expensive) box?
 
kornbln said:
isn't it easier to just use the deepest box you can, or does the extra cost add up too much? how much time does it take to figure box fill vs just using a deeper (more expensive) box?
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A case of 18 in? is about $21. 21 in? is about $23. I'll take the 21s and never worry about fill.
 
kornbln said:
isn't it easier to just use the deepest box you can, or does the extra cost add up too much? how much time does it take to figure box fill vs just using a deeper (more expensive) box?
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You still eventually need to figure box fill, and should be able to do it also. I buy the deepest 1gang boxes that will fit in a 2x4 wall, but its the switches and kitchen counter tops that can be a fill problem, think of 3 gang box with all 4 ways, feeds, loads etc, sometimes you just need to know where you stand.
 
stickboy1375 said:
Actually the way I read it, Each yoke or strap based on the largest conductor connected to a device or equipment supported by that yoke or strap.

so if I had a 2 gang box with 14awg going to a switch and a 12awg going to a gfci, then my device fill would be 8.50 not 9.00
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That is correct. If the box contains different size conductors that terminate on devices you would use the conductor size that terminates on each device to determine the deduction.
 
celtic said:
What happens in the case of a range or dryer recept.?

;)

480sparky said:
How many 10s, 8s and 6s do you splice in your dryer and range receps?
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I fail to relevance of the conductor size when it concerns box fill counts.
At some point the size of the conductor matters, but for box fill count in my question - one needs only to count the conductors/fill.

frizbeedog said:
Two point conversion Cowboy.

:wink:
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LOL...TY.
 
stickboy1375 said:
. . . think of 3 gang box with all 4 ways, feeds, loads etc, . . .
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In my ever-so-humble opinion, with careful and neat wire dressing, you should be able to fit all of the wires attached to a device within that device's share of the box volume (at least, in theory.)

I things are tight, I will completely re-make the connections in a box first; if the box ends up needing to be replaced anyway, that work still needs to be done. I can usually judge when looking.

I have had to replace boxes when replacing duplexes with GFCI's and dimmers, though, when smaller boxes were originally installed, especially the old black-painted steel boxes used with BX.

In reality, they do get to share the space. In 3-gang and larger boxes, I lay the EGC's, neutrals, and incoming and outgoing feed bundles horizontally, and then the device wires vertically.
 
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